1. Technical Field
This invention relates to a resin tube-equipped quick connector, and more specifically to a resin tube-equipped quick connector for connecting a fuel-transporting resin tube to a mating pipe.
2. Background Art
A resin tube has heretofore been widely used for fuel transporting purposes, for example, for transporting fuel within a fuel tank to an engine.
This resin tube is connected to a vehicle body-side mating pipe to form a piping system for fuel transporting purposes.
Heretofore, for connecting this resin tube and the mating pipe together, a quick connector capable of effecting this connection with a one-touch operation has been used.
A quick connector of this kind is disclosed, for example, in JP-A-11-201355. FIGS. 8A, 8B, 9A and 9B show a specific example of the construction of this quick connector.
In these Figures, 200 denotes a resin tube, and 202 denotes a mating pipe to which this resin tube 200 is to be connected.
An engagement convex portion (pipe-side engagement portion) 204, projecting in an annular shape, is formed on an outer peripheral surface of the mating pipe 202.
206 denotes the quick connector which includes a connector body (here made entirely of a resin) 208, a retainer 210, and O-rings 212 and a bushing 214 which serve as seal members.
The connector body 208 has a retainer holding portion 216 at one axial side thereof, and also has a press-fitting portion 218 at the other side thereof.
The press-fitting portion 218 is a portion for being press-fitted into the interior of the resin tube 200 in the axial direction, and annular projections 220 of a sawtooth-like cross-section, each having an acute-angled distal end, are formed respectively on a plurality of axially-different portions of an outer peripheral surface of this press-fitting portion.
By press-fitting this press-fitting portion 218 into the interior of the resin tube 200, the connector body 208 is connected to this resin tube 200.
At this time, the annular projections 220, formed on the outer peripheral surface of the press-fitting portion 218, bite into an inner surface of an end portion of the resin tube 200 bulgingly deformed as a result of the pressing fitting, thereby preventing the withdrawal of the resin tube 200.
Incidentally, an annular groove is formed in the press-fitting portion 218, and an O-ring 222 is held in this groove, and this O-ring 222 forms an airtight seal between the press-fitting portion 218 and the resin tube 200.
The retainer holding portion 216 is a portion for receiving the retainer 210 therein to hold the same, and the connector body 208 is connected to the mating pipe 202 through this retainer 210.
A retaining engagement portion (body-side retaining engagement portion) 224 for retaining engagement with the retainer 210 is formed at a front end of this retainer holding portion 216.
On the other hand, the retainer 210 is a resin-made member having a generally annular shape as a whole, and can be elastically deformed radially.
An engagement recess portion (retainer-side engagement portion) 225 with which the engagement convex portion 204 of the mating pipe 202 can be engaged from a radially-inward side, as well as a retaining engagement groove (retainer-side retaining engagement portion) 226 which can be fitted to the retaining engagement portion 224 of the connector body 208 also from the radially-inward side to be retained in the axial direction, is provided on this retainer 210.
This retaining engagement groove 226 is retainingly engaged with the retaining engagement portion 224 of the retainer holding portion 216, so that the retainer 210 is held in a fixed condition in the axial direction by this retainer holding portion 216.
Further, an inner peripheral cam surface 228 and an outer peripheral cam surface 230, each having a tapering shape, are formed respectively on an inner peripheral surface and an outer peripheral surface of this retainer 210.
When the mating pipe 202 is inserted into the interior of the retainer 210 in the axial direction, the inner peripheral cam surface 228 abuts against the engagement convex portion 204 to guide the movement thereof, and also causes the retainer 210 to make an expanding motion elastically as a whole by a cam effect in accordance with the movement of the engagement convex portion 204, thereby allowing the passage of the engagement convex portion 204.
Then, when the engagement convex portion 204 reaches the position of the engagement recess portion 225, the retainer 210 is restored into its original shape as a whole, and simultaneously with this, the engagement convex portion 204 is fitted in the engagement recess portion 225, so that these portions are fixed to each other in the axial direction.
On the other hand, when the retainer 210 is inserted into the retainer holding portion 216 of the connector body 208 in the axial direction, the outer peripheral cam surface 230 abuts against the retaining engagement portion 224 to cause the retainer 210 to make a diameter-reducing motion elastically as a whole, and causes the retaining engagement groove 226 to be retainingly engaged with the retaining engagement portion 224 with this diameter-reducing motion.
Operating finger grips 231 are provided at a front end portion of the retainer 210, and by applying a force to the operating finger grips 231, the retainer 210 can be caused to make a diameter-reducing motion.
In this quick connector 206, the retainer 210 is held in the retainer holding portion 216 of the connector body 208, and in this condition the mating pipe 202 is inserted into the interior of the retainer 210 in the axial direction.
At this time, the retainer 210 is elastically forced open in an expanding direction by the engagement convex portion 204 of the mating pipe 202, and then makes a diameter-reducing motion when the engagement convex portion 204 reaches the engagement recess portion 225, and also the engagement convex portion 204 is engaged in the engagement recess portion 225.
Incidentally, the retainer 210 may be beforehand attached to the mating pipe 202, and in this condition the mating pipe 202 may be inserted, together with the retainer 210, into the connector body 208.
At this time, the retainer 210 once makes a diameter-reducing motion, and thereafter makes an expanding motion when the retaining engagement groove 226 reaches the position of the retaining engagement portion 224, so that the retaining engagement groove 226 is retainingly engaged with the retaining engagement portion 224.
The O-rings 212 and the bushing 214 which serve as the seal members are mounted within the connector body 208 at a region deeper than the retainer holding portion 216, and are held therein. When the mating pipe 202 is inserted into the connector body 208, the O-rings 212 and the bushing 214 are brought into air-tight contact with an insertion end portion 232 of the mating pipe 202, that is, the outer peripheral surface of the insertion end portion 232 disposed closer to the distal end of the mating pipe than the engagement convex portion 204 is disposed, thereby forming an air-tight seal between the mating pipe 202 and the connector body 208.
Although the two O-rings 212 are used in FIG. 8A, there are occasions when only one O-ring 212 is used in order to achieve a compact design as shown in FIG. 8B.
As will be appreciated from the foregoing, in the connection using such quick connector 206, the resin tube 200 can be easily connected to the mating pipe 202 with a one-touch operation.
For example, a tube, having an inner diameter of 6 mm and an outer diameter of about 8 mm, has been used as the above conventional resin tube 200, and it has been used in a piping system as shown in FIG. 10.
In this piping system, fuel within a fuel tank 234 is supplied via a supply passage 238 under a constant pressure by a fuel pump 236, and this fuel is injected from an injector 240 into a cylinder 242 of an engine, and excess fuel is retuned to the fuel tank 234 via a return passage 244.
From the viewpoint of the design of the piping system or from the viewpoint of cost reduction, it is considered preferable that the above pipes and resin tube should be lightweight and small in diameter.
On the other hand, in recent years, there has been used a piping system (a so-called fuel returnless system) in which only a necessary amount of fuel, that is, an amount to be consumed, is supplied to the engine without supplying excess fuel from the fuel tank 234, and the returning of the excess fuel to the fuel tank 234 as in the piping system (a so-called fuel return system) of FIG. 10 is not carried out.
In this fuel returnless system, only the necessary amount of fuel is supplied, and therefore when a resin tube, having the same inner diameter as that of the resin tube of the piping system of FIG. 10, is used, the accumulation of the fuel is liable to occur, and the accumulated fuel is vaporized within the piping by the atmosphere within an engine room, so that an engine speed is liable to become unstable.
In this case, it is preferred to use a small-diameter resin tube with an inner diameter, for example, of not larger than 5 mm as the resin tube so that the accumulation of the fuel will not occur.
With respect to so-called compact vehicles with a small engine displacement, such as a mini-vehicle, an automotive two-wheeled vehicle, an automotive three-wheeled vehicle and an ATV (All Terrain Vehicle), it is preferred to use a small-diameter resin tube with an inner diameter of not larger than 4 mm (for example, 3.5 mm) for the purpose of suppressing the accumulation of fuel, and it is more preferred to use a small-diameter resin tube with an inner diameter of not larger than 3 mm (for example, 2.5 mm).
However, in the case of using such a small-diameter resin tube, when the press-fitting portion 218 of the quick connector 206 is press-fitted directly into the resin tube, this press-fitting operation fails halfway, and when trying to forcibly press-fit it, the resin tube is buckled, so that the resin tube cannot be connected to the mating pipe 202 by the use of such a quick connector 206.